FIGS. 1 to 4 show four curves relating to motor rotation speed controls, which represent relationships between rotation speeds of motors and signals for controlling the rotation speeds of the motors. The signals may be an electrical signal such as a current signal, a voltage signal, or a Pulse Width Modulation (PWM) signal having a duty cycle. In the four figures, the abscissa represents a duty cycle of a PWM signal for controlling a rotation speed of a motor, and the ordinate represents the rotation speed of the motor.
It can be seen from comparisons between FIGS. 1, 2 and FIGS. 3, 4 that: in FIGS. 3 and 4, the rotation speed of the motor can jump to a relatively high rotation speed from a low speed or from a static state at a specific duty cycle; and as shown in FIG. 3, when the duty cycle is about 30%, the motor rotates at about 1600 RPM (Revolutions Per Minute) sharply increased from about 800 RPM; as shown in FIG. 4, when the duty cycle is about 30%, the motor rotates at about 1600 RPM sharply increased from 0 RPM; however, the rotation speeds of the motors in FIGS. 1 and 2 do not have such jumps.
In some application scenarios, the curves relating to motor rotation speed controls shown in FIGS. 3 and 4 are desired. For example, in fans of home appliances and fans of Central Process Units (CPUs), it is desirable that the rotation speed of the motor is capable of jumping at a certain duty cycle.
However, in the related art, only the control curves shown in FIGS. 1 and 2 can be realized and the control curves shown in FIGS. 3 and 4 cannot be realized.